Manual hardware unit tests
A driver may choose to implement the
run_unit_tests() driver op, which
provides the driver a hook in which it may run unit tests at system
initialization with access to the parent device. This means the driver may test
its bind and unbind hooks, as well as any interactions with real hardware. If
the tests pass (the driver returns
true from the hook) then operation will
continue as normal and
bind() will execute. If the tests fail then the device
manager will assume that the driver is invalid and never attempt to bind it.
Since these tests must run at system initialization (in order to not interfere
with the usual operation of the driver) they are activated with a
kernel command line flag. To enable
the hook for a specific driver, use
driver.<name>.tests.enable. Or for all
driver.tests.enable. If a driver doesn't implement
then these flags will have no effect.
run_unit_tests() passes the driver a channel for it to write test output to.
Test output should be in the form of
fuchsia.driver.test.Logger FIDL messages.
The driver-unit-test library contains a helper class that integrates with
zxtest and handles logging for you.
TODO(fxbug.dev/51320): Fill out more detail here.